.. _wrrf_interactive: WERF Benchmark WRRF Configurations ==================================== Process flow diagrams for all 18 water resource recovery facility (WRRF) configurations as described in In Zhang et al., 2026 [1]_. These configurations were based on the net-zero energy solutions for WRRFs report by the Water Environment Research Foundation (WERF, now a part of the Water Research Foundation, WRF) [2]_. Source codes for these configurations can be found in the `werf EXPOsan module `_. To create any of the system configurations, use the following code, replacing ``B1`` with the desired configuration code (e.g., ``B2``, ``C3``, etc.). .. code-block:: python from exposan.werf import create_system B1 = create_system('B1') B1.simulate(method='BDF', t_span=(0, 400)) B1.diagram(file='B1', format='html') Valid configuration codes are: B1, B2, B3, C1, C2, C3, E2, E2P, F1, G1, G2, G3, H1, I1, I2, I3, N1, N2. .. figure:: ../images/wrrf_configs_light.png :class: only-light .. figure:: ../images/wrrf_configs_dark.png :class: only-dark Distinguishing features of benchmark WRRF configurations. A WRRF configuration is referred to as a unique combination of a liquid code (a) and a solid code (b) as defined in [2]_. Configurations followed by a star (\*) are implemented in ``EXPOsan``. .. raw:: html Reading the Diagrams -------------------- Every diagram uses the same convention: liquid train across the top with the bioreactor zones in the middle, mixed-liquor recycles (MLR) above the zones, return activated sludge (RAS) below them; solids train across the middle; reject water (centrate + thickener supernatants) returned to the head of the plant along the bottom. ``PC`` Primary clarifier · ``SC`` Secondary clarifier · ``DW`` Dewatering ``GT`` Gravity thickener · ``MT`` Mechanical thickener · ``MBR`` Membrane bioreactor ``AD`` Anaerobic digester · ``AED`` Aerobic digester ``RWW`` Raw wastewater · ``ML`` Mixed liquor ``PE`` Primary effluent · ``PS`` Primary sludge ``SE`` Secondary effluent · ``WAS`` Waste activated sludge The configurations are categorized based on their treatment goals: * rBOD for basic BOD removal (r for readily): B (with primary clarifier) and C (without primary clarifier) series. * NIT for nitrification: E (aerobic digestion) and F series (anaerobic digestion). * BNR for biological nutrient removal: G (Johannesburg), H (4-stage Bardenpho+chemicals), I (5-stage Bardenpho), N (5-stage Bardenpho+MBR) series. .. raw:: html B Series: rBOD with Primary Clarifier ------------------------------------- Conventional six-zone aerobic activated sludge with short SRT (~2 d) — only BOD removal, nitrifiers wash out. The three B variants differ only in the solids train (AD, AED, or no digestion). .. raw:: html

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C Series: rBOD without Primary Clarifier ---------------------------------------- Same six-zone aerobic activated sludge as the B series but without primary clarification — all influent organics enter the bioreactor directly, increasing aeration demand. The three C variants differ only in the solids train (AD, AED, or no digestion). .. raw:: html

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E Series: NIT with Aerobic Digestion ------------------------------------ Longer SRT (~6 d) retains nitrifiers for NH₄⁺ oxidation. E2-P adds primary clarification to the E2 liquid train. .. raw:: html

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F Series: NIT with Anaerobic Digestion -------------------------------------- Compared to E2-P, F1 differs in solids treatment by using anaerobic digestion. .. raw:: html

G Series: BNR with Johannesburg Process --------------------------------------- BNR configurations with primary clarification. G1–G3 use the Johannesburg step-fed process with external carbon for EBPR; .. raw:: html

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H Series: BNR with Chemical P Removal ------------------------------------- H1 combines chemical phosphorus removal (Fe:sup:`3+`/Al:sup:`3+`) with a 4-stage Bardenpho bioreactor and external carbon. .. raw:: html

I Series: BNR with 5-stage Bardenpho ------------------------------------ Five-stage Bardenpho without primary clarification — raw wastewater provides carbon for denitrification and EBPR without external dosing. The three I variants differ only in the solids train (AD, AED, or no digestion). .. raw:: html

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N Series: BNR with MBR ---------------------- Five-stage Bardenpho liquid train with a completely-mixed membrane bioreactor (MBR) replacing the conventional secondary clarifier. N1 includes primary clarification and anaerobic digestion; N2 omits primary clarification and uses aerobic digestion. .. raw:: html

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.. References .. [1] Zhang, X.; Rai, S.; Wang, Z.; Li, Y.; Guest, J. S. An Agile Benchmarking Framework for Wastewater Resource Recovery Technologies. npj Clean Water 2025, 9 (1), 4. https://doi.org/10.1038/s41545-025-00537-4. .. [2] Tarallo, S., Shaw, A., Kohl, P. & Eschborn, R. A Guide to Net-Zero Energy Solutions for Water Resource Recovery Facilities. https://iwaponline.com/ebooks/book/293/ (2015).